Process of smelting.



" vUNITED STATES PATENT OFFICE.-r j

WILLIAM H. ADAMS AND FREDERICK POWELL, OF PORTLAND, OREGON, ASSIGNORS OF TWENTY-FIVE ONE-HUNDREDTHS TO SAID ADAMS,

FIFTEEN ONE-HUNDREDTHS/ TO SAID POWELL, AND SIXTY ONE- HUNDREDTHS TO THE LADD METALS COMPANY,` A CORPORATION OF OREGON.

PROCESS OF SNIELTING.

Patented oct. 30,1906.

Application filed July 16, 1904. Serial No# 216,801.

To @ZZ whom, t .may concern:

Be it known that we, WILLIAM H. ADAMS and FREDERICK POWELL, citizens of the United States, residing in Portland, in the county of Multnomah and State of Oregon,

have invented `a new and useful Improvement in the Process of Smelting, of which the following is a specification.

Our invention consists in an improvement Io in the method of smelting ores, particularly those requiring a high temperature for their reduction or for their fusion. In the common practice of smelting in stack or upright furnaces the ore, fluxes, and fuel are introduced at or near the top of the furnace, air is introduced through a number of twyers through the walls of the furnace near the bottom, and fusion-takes place as a result of the combustion of the fuel in immediate contact with the ore. Reduction of oxids to metallic form, as in iron smelting, or oxidation of certain elements, such as. sulfur in copper smelting, Vtakes place according to the relativequantity of fuel, the height of the furnace, andthe amount of air introduced.

EconomyT in smelting means the smelting of the greatest number of pounds of ore with the smallest amount of fluxes and fuel. In the effort to reduce the fuel to thelowest pos- 39 sible percentage a smallmargin of safety is sometimes allowed..l The result of this is that a slight change in thecharacter or composition of the Ore or carelessness on the part of the feeder -may cause the furnace to freeze. This means that there'is not sufficient fuel in the furnace at the fusion zone to melt the charge Or. make a fluid slag. As this fusion zone is near the twyers at the bottom of the furnace and the only way to get fuel into the furnace is through thek top, there is no remedy but to increase the fuel at the top in the hope that thefurnace will keep working long enough for this to get down to the right spot before the freeze-up becomes a fact land the furnace has to be cleanedxout and started anew. i

The principal improvement heretofore introduced tending to reduce thc fuel required and `at the same time keep the furnace hot at 5o the bottom is the hot blast.. The airis heated before it enters the furnace. This is common practice in iron smelting and has recently been introduced in copper smelting with beneficial results.

One serious difficulty smelters have to con- 5 5 tend with is the loss of fine particles of Ore blown out of the furnace mechanically by the blast. This makes the smelting of fine ores in astack impracticable unless they are first briqueted. In large plants the flue-dust and 6o fine ore are smelted in reverberatories or bri' quoted and returned to the stack. In small n plants, where the additional furnace is` not l practicable, for some reason the loss in dust is a serious item Or briqueting a serious exi pense. l

One indispensable requisite for smelting in V, Y a stack-furnace by the present practice is coke as fuel. Reverberatory furnaces are fired with coal or wood. Inmany localities'the 7o cost of coke or coal is prohibitory and the available wood is of such poor quality that smelting is economically impossible when grate-.fires are used..

Ourinvention consists in an improvement '7 5 in the method of smelting in stack-furnaces wherebythe difficulties met with in smelting as commonly practiced are overcome. By our method coal or wood is used as afuel and the freezing-up of a furnace, due toV exhaus- 8o v tion of the fuel before it descends to the 5 fusion zone, is impossible.

The item of fluxes may be materially reduced by our method, because owing vto the manner in which the air and fuel are introduced a higher temperature can be secured at the bottom of the furnace than by any method at present in use. A much more silicious or otherwise difficultly-fused slag can A' therefore be run with safety, which means 9o less fluxes.- By our method the greater part ofthe fuel is converted into gas before its introduction into the furnace and when introduced it enters at the bottom instead of the top. The greatest heat .is therefore insured 'at the proper place and a freeze-up is practically impossible.

Owing to the form of apparatus required to carry on our method of smelting, a means l. is provided by which flue-dust and fine ore Icoy may be introduced at the bottom of the furnace instead of the top, thus subjecting them to a smelting heat where they cannot be blown out of the furnace.

In the accompanying drawings, which form a part of this specification, we have shown our preferred form of apparatus for practicing the invention.

In the drawings, Figure l is a vertical section on the line A B of Fig. 2, and Fig. 2 is a horizontal section on the line C D of Fig. 1.

Referring to the drawings, F is a furnacestack of the type common in snielting copper ores. The lower portion is composed of steel water-jackets G, having openings g for the admission of air under pressure, as in ordinary practice.

H is the hearth or crucible of the furnace, which is extended on one side beyond the jackets of the stack. This extension is covered with an arch of fire-brick, thus forming a flue connecting with the generator P. IVe

prefer the form of gas-generator shown, because it is especially adapted to our method of smelting, for the reason that it is capable of delivering hot gas into the furnace under any pressure desired. Openings I are provided, through which any desired amount of air is forced into the Hue or hearth H, securing combustion of any desired portion of the gas before entering the stack, and J is an opening through which fine ore is introduced into the hearth.

K is a tap-hole at the bottom of the hearth for removing metal or matte, andIiis an opening in the hearth for reinovin slag. The chamber is preferably elliptica in form and is elongated at the base just above the grate T, so as to form an increased area at the Zone of incandescence. In this manner we insure an additional mass of fuel iii this zone, which we find desirable to thoroughly decompose and fix the products of com ustion and the volatile elements of the fuel. The fuel is admitted to the chamber by the feed device S, the operation of which will be understood.

Sv re resents a valved feeder, through which liquid ydrocarbons may be admitted to the generator for enriching the gas. A waterseal ash-pan is shown at V, and W is the airpipe connected with a fan or pump, whereby a pressure-blast may be created through it. Air is admitted to the chamber of the generator through the ports w.

X is the outlet through which the gas enters the reverberatory hearth or flue, and, as shown, it is located in a plane below the top of the fuel and leads from the end of the elongation of the chamber above mentioned. A zone of incandescence is thus insured throughout the longest part of the chamber, and as all the products of combustion, aswell as the volatile elements of the fuel, must pass through said zone the decomposition thereof is thorough.

W is an additional air-inlet for su plying air to the bottom of the grate belIdw the ports w.

N is a vertical diaphragm placed transversely across the bottom of the generator below the grate and extending downward into the water in the ash-pan. It forms a close junction at its ends with the depending skirt V', which surrounds the grates ace and extends down into the water of t e ash-pan, so that said diaphragm is enabled to limit the area of the grate through which air supplied by the inlet W in ay have access to the grate. The skirt, in conjunction with the asli-paii, effects the water seal and prevents the entrance of air to the bottom of the grate, except such as is admitted by the air-inlet above described. Steam may also be admitted through the inlet W by means of the steam-pipe W2.

Y re resents poke-holes.

It will be understood that thc air is introduced into the furnace under pressure from a blower, as in common practice in smclting, and that the gas-producer is operated with forced blast from an independent blower giving a pressure slightly in excess of that of the furnace-blast.

Our method of siiieltiiig, carried on in an apparatus substantially of the forni described, is as follows: The gas generator is first started, using either wood or coal, it being understood that if wood is to be burned the generator is required to be somewhat larger than for coal. A suflicient amount of aii is admitted in the hearth through the openings I I to burn the gas. If the hearth is new and cold, a re of wood must be started iii it to secure the ignition of the gas. Then a quantity of wood cut to about the size of ordinary stoveewood-tliat is, twelve to sixteen inches long and from six to eight inches thick--is introduced in the stack sufficient to fill it somewhat above the twyers, and the blast is turned on at this point. This fuel is immediately ignited by the gas-flame. Lump coal (or wood) is now introduced sufficient to fill the stack about half full. After this is thoroughly ignited ore, fluxes, and fuel are charged in regular order. If coal is used, lumps only are used in the stack, the fine ortioii going to the gas-generator. If woo is used, it should be cut up as described. In either case the chief object of the fuel in the stack is to keep the ore from fusing into a mass that would obstruct the passage of the gas and the blast, the main source of heat being the gas. The ore should be screened and only the coarse ore charged in the stack, the fines being introduced into the hearth of the furnace at intervals through the opening J or through a door at the side. During the charging of fine ore the blast on the furnace and on the generator are both reduced to a point where the natural draft of the stack IOC ITO

. the ore.

will prevent fire bursting from this chargingdoor opening. The hearth is soon filled with molten matter up to the level ofthe slag-tap, which is left open, and the slag allowed to run through a raised spout which traps the blast until the accumulation of matte or metal requires tapping from the lower tap-hole. This methodallows a much better opportunity for matte or metal to settle out of the slag than is possible in any form of settler or forehearth. The slag is held at the highest temperature while this settling is accomplished. Itis therefore practicable to make clean slags when they lare so silicious as to flow but slowly from the ordinary furnace or so high in specific gravity that the matte or metal settles slowly. The use of the outside settler is therefore unnecessary in ordinary cases.

Owing to the method of introducing fine ores and the screening out of all fine material from the ore charged in the stack, smelting by our method makes practically no flue-dust By our method of smelting by means of a gasflame forced into the base of a stack and means for introducing air through twyers in the stack itself or into the flue leading to the stack it is possible to regulate the action within the furnace by admitting the proper quantity of air at the proper place, so as to produce a reducing effect Where deoXidation or reduction of oXid ores is re uired or an oxidizing effect where the oX ation of any element in the charge is desirable.

The twyers or air-inlets through the jackets at the base of the stack supply air for the combustion of gas as it passes up the stack and for the combustion of the fuel fed with The twyers in the flue supply air for combustion of the gas or any portion of it before it reaches the stack. An oxidizing flame is thus produced with an excess of air or a reducing flame with a limited quantity. The fuel fed with the ore assists with the smelting, but is not required in proportion sufficient to smelt the charge, nor is it required to be of a character or quality necesf sary to produce a smelting heat, soft coal or wood being sufficient. Some classes of ore not tending to agglomerate would require no fuel in the stack. f

We claim- 1. An improved method of smelting ores consisting in subjecting a column of the coarse ore to the heat of a gas-name generated from a klong horizontal body of fuel in the' lower portion of which a horizontal zone of incandescence is established, and through which zone the products of combustion and volatile parts of the fuel must pass burning p such gas in a suitable flue leading to the base of the column of ore, the blast being under suflicient ressure to force the heat upward through tliie column, and adding to the bath of melted ore at the base of such column the fine ore to be smelted therein combined'with fresh air.

2. The improved method of smelting consisting in converting a lon horizontal body of fuel into gas by establis 'ng a zone of incandescence through the lower portion of the fuel and compelling the products of combustion and volatile vparts of the fuel to pass through such zone, burning the gas in a suitable flue leading to the base of a column of ore, and forcing the resultant heat and products of combustion upward through said column of ore.

3. The improved method of smelting consisting in converting a long horizontal body of fuel into gas by establishing a zone of incandescence through the lower portion of the. fuel A and compelling the products of combustion and volatile parts of the fuel to pass through such zone, burning the gas in a suitable flue leading to the base of a column of ore, feeding fine ore and air through such flue to the base of the ore column and forcing the heat and4 flame upward through the column.

WILLIAM H. ADAMS. FREDERICK POWELL Witnesses ZERA- SNOW, S. L. BRENNAN. 

